Certain parts of gas turbines which are located near or in the combustor region of a gas turbine require isolation in order to continue to operate. This disclosure relates to a method of cooling a bearing on the compressor turbine which because of the nature of the turbine construction (i.e. split shaft type) is located in an area close to where combustion takes place in the turbine. Bearings in this region have been cooled in the past by ducting cooling air from an intermediate stage on the compressor to the bearing to be cooled. Problems which occurred in the past generally pertain to undue heating of the cooling air whilst passing through the combustor area of the turbine and ineffective cooling of the bearing in question because of improper or insufficient air flow over the bearing surfaces.
Cooling air has been ducted up the compressor shaft to cool the bearings located in hot regions, but the problems associated with hollow or ducted shafts are many and are avoided by the present invention. It must also be remembered that any cooling air which is delivered to the region of the bearing in question must be removed from it by some suitable means, and the removal of such cooling air must be done with as little inconvenience or disruption of machine operation as possible.